In 3rd generation cellular systems for TDD and FDD almost all resources are fully allocated and controlled by the Controlling Radio Network Controller (C-RNC) that controls the Node B radio resources. For Dedicated Channels (DCH) the C-RNC allocates a fixed amount of resources from the resource pool and assigns it to service the DCH. An example of a DCH service is voice services. For data type services, the CRNC can allocate Downlink Shared Channels (DSCH). Examples of a DSCH service are data services such as Web download, file transfer protocol (Ftp) services or e-mail. Multiple users share this channel over time, and the scheduling of this channel, for example, which user gets access to the channel, is performed in the C-RNC.
These resources are managed by the C-RNC which can decide how much of the resources of a cell is allocated to DCH services and how much is allocated to DSCH services because each resource can only serve one type of service (DCH or DSCH) at a single moment, however resources can be moved back and forth between the two resource pools as is needed.
An additional complexity occurs in the resource allocation of the DSCH in the C-RNC since it is a shared resource that handles multiple services of variable data rates. The maximum amount of resources that are requested by the sum of the users can frequently exceed the amount of the resources in the pool allocated to this type of service. This is possible since all users statistically will not want to transmit at its highest allowed rate simultaneously. Therefore, data service users need to be monitored to determine not only that the radio resources are utilized efficiently but also that the users are not excessively over-provisioned on the available resource, since either condition would cause the users Quality of Service (QoS) to deteriorate.
The C-RNC must answer the following general questions to have optimal knowledge of the operation of the high-speed downlink packet access (HSDPA) service. The first question is, how well is the QoS requirement fulfilled for each user? Particularly, it would need to determine whether all of the operational parameters are set to optimal levels for both the shared and dedicated services. The second question is how well are the overall resources utilized by the two types of services (dedicated and shared service)? Is there an optimal resource split between dedicated and shared services given the current usage/demand of each service?
Yet another question is how much does it cost the overall system performance by adding a user of certain QoS requirement to the cell? This is particularly an issue for shared services where the service rates a user really needs are usually variable over time and the resource allocated to the user is usually over-provisioned.
In most services the C-RNC can readily answer these questions. For a particular user with dedicated service, the C-RNC allocates a fixed amount of resources since the amount of resource used by the user is pretty static over time. For a user of variable data rates with shared service, the C-RNC has enough information to understand how well resources are being used among the users.
However, the High Speed Downlink Packet Access (HSDPA) service uses a new channel; a High Speed Downlink Shared Channel (HS-DSCH) to provide higher data rates for data services than the DSCH. The HS-DSCH service is based on the Node B more dynamically adapting the transmission to better service the users that have data to be transmitted. Therefore the C-RNC no longer schedules the data to be transmitted at a particular moment or the actual resources used for that transmission. The C-RNC basically assigns a given amount of power and the resources in the data resource pool to the Node B and the Node B dynamically schedules the users' data based on current radio conditions.
The consequences of this architecture change in the functionality of data services in the C-RNC leaves it without some of the basic information it has had for other services. Consequently, questions asked before such as: (1) how well the QoS has been fulfilled; (2) the overall resource utilization; and (3) the effect of adding a user to the system, cannot be completely answered.